Yes, you can. Air bubbles that make their way into the upper part of a dirt separator housing will be automatically removed if an air vent is installed. Our brass dirt separators, such as the 5462 Series DIRTCAL and 5463 Series DIRTMAG have a 1/2" female NPT top connection so the 502043A MINICAL or the 502243A or 502343A VALCAL will fit perfectly. Our larger, steel flanged dirt separators, such as the 5465 DIRTCAL, NA5465 DIRTCAL (with ASME/CRN), or the 5465 DIRTMAG Series, have a 3/4" male NPT top connection so the 501502A MAXCAL air vent is the perfect fit for those. That being said, we highly recommend installing a dedicated air separator, such as a 551 Series DISCAL or a combination air/dirt separator such as the 546 Series DISCALDIRT in every hydronic system. These devices automatically remove all air down to the micro-bubble level, which an air vent alone will not do.
Check out our idronics issue #15 (Separation in Hydronic Systems) for detailed information on air removal.